High strengthening of a steel sheet that is a raw material has been in progress so as to realize compatibility between a weight saving of a body, components, and the like of a vehicle, and safety. Generally, when the strength of the steel sheet increases, ductility decreases, and thus formability is damaged. Therefore, the balance of strength and ductility is necessary in order to use the high-strength steel sheet for the members of the vehicles. For this requirement, hitherto, a so-called TRIP steel sheet, in which transformation induced plasticity of retained austenite is used, has been suggested (for example, refer to Patent Document 1 and Patent Document 2).
However, the TRIP steel has characteristics in which strength and ductility are excellent, but generally, local deformability such as hole expansibility is low. Furthermore, so as to progress the weight saving of the vehicle body, it is necessary to increase a use strength level of the high-strength steel sheet beyond that of the related art. Therefore, for example, so as to use the high-strength steel sheet for underbody components, it is necessary to improve local deformability such as hole expansibility.